KVM: PPC: Book3S HV: Allow DTL to be set to address 0, length 0
Commit 55b665b026 ("KVM: PPC: Book3S HV: Provide a way for userspace
to get/set per-vCPU areas") includes a check on the length of the
dispatch trace log (DTL) to make sure the buffer is at least one entry
long. This is appropriate when registering a buffer, but the
interface also allows for any existing buffer to be unregistered by
specifying a zero address. In this case the length check is not
appropriate. This makes the check conditional on the address being
non-zero.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 8b3c470..812764c 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -811,9 +811,8 @@
addr = val->vpaval.addr;
len = val->vpaval.length;
r = -EINVAL;
- if (len < sizeof(struct dtl_entry))
- break;
- if (addr && !vcpu->arch.vpa.next_gpa)
+ if (addr && (len < sizeof(struct dtl_entry) ||
+ !vcpu->arch.vpa.next_gpa))
break;
len -= len % sizeof(struct dtl_entry);
r = set_vpa(vcpu, &vcpu->arch.dtl, addr, len);